Materials selection procedure for RF-MEMS

In this letter, we present a materials selection based on the Ashby’s methodology to optimise the choice of bridge’s material in radio-frequency applications. Two material indices are defined to minimize the intrinsic residual stress due to sputtering deposition process and to maximize the quality factor, respectively. The selection procedure gives aluminium, copper and gold as the best materials. Aluminium and copper have to be rejected due to a sensitivity to oxygen, humidity and thus possible oxide formation. Experiments on gold have been performed and confirm this selection.